How stick spiders living on Hawaiian Islands again
and again- New research examined
Around 2 to 3 million years ago, a group of spiders set sail and arrived to the Pacific Ocean to Hawaii.
These spiders are parasitic of other spiders, who
built their webs. These spiders invading their webs and steel insects that have
been caught. But in Hawaii there are no webs to rob. So they survive by
trapping and eating other spiders.
A new spices is evolved from that first spider,
which live on rocks and another one which lives on plant leaves and then 11
more spices are evolved.
Charles Darwin
first mentions this as the "adaptive
radiation" in the Galapagos Islands.
The study, which appears in Current Biology, show
that evolution has led to a predictable and independently evolved set of
similar forms in spiders on each island.“This very predictable
repeated evolution of the same forms is fascinating because it sheds
light on how evolution actually happens,” says Rosemary Gillespie, a professor
of systematic entomology at the University of California, Berkeley and lead
author of the paper. “Such outstanding predictability is rare and is only found
in a few other organisms that similarly move around the vegetation.”
“This study provides insights into a fundamental
question about the origins of biodiversity, but also presents a remarkable
story that can call attention to the need for conserving nature in all of its
forms,” says coauthor George Roderick, professor and chair of the department of
environmental science policy and management.
Stick spiders have evolved and differentiated from a single species on the same island, the study found. So, spider types
on any one island were generally more closely related to very different looking
spiders on the same island than to spiders that looked the same on other
islands.
“You can find these spiders
in pretty much every habitat on each island,” Gillespie said. “This
really detailed and finely tuned repetition of evolution of the same form is
really quite uncommon.”
The spiders can be grouped into three distinct
ecological types, called ecomorphs: A
brown one that lives in rocks; a gold one that lives in under leaves, and a
white one that’s a matte color and lives on lichen.
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